Messages in this thread | | | Date | Sun, 01 Oct 2006 13:28:41 -0400 | From | Jeff Garzik <> | Subject | Re: [PATCH] fs/eventpoll: error handling micro-cleanup |
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Davide Libenzi wrote: > On Sun, 1 Oct 2006, Jeff Garzik wrote: > >> Davide Libenzi wrote: >> >>> I just tried a `find /usr/src/linux-2.6.16/ -type f -exec grep -H -C 2 >>> PTR_ERR {} \;` >>> and looked at the cases where the error variable is assigned in any case >>> before the test. Same code pattern as, like: >>> >>> error = -EFAULT; >>> if (copy_from_user(...)) >>> goto kaboom; >> No, that's quite different. I'm talking about >> >> ptr = get_a_pointer_from_somewhere() >> error = PTR_ERR(ptr) >> >> See the difference? The error variable is directly assigned from a >> potentially-valid pointer. > > So? Is PTR_ERR() defined and documented in a way that, if called with a > valid pointer, has an unexpected/faulty behaviour?
When called with a valid pointer, the value assigned to the return-code integer is essentially a random number.
> Again, I don't care either ways, but don't tell me you're not sure about > the countless occurrences. Take a look at: > > `find $LINUXSRC -type f -exec grep -H -C 2 PTR_ERR {} \;`
Perhaps 1 out of every 100 or so hits from this find(1) is unprotected by IS_ERR(). IOW, what I've been describing here is quite rare.
Jeff
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